Underreamer.



H. GEARING.

UNDBRRBAMER. BPLIOATION FILED APB l5, 1913 Patented Mar. 31, 1914.

thus constituting a rack and pinion engagement between the dogs and the stem. The dogs are formed to-lie approximately wit-hin the slots 16 when the block 9 is in elevated position and the cutters are collapsed, and to extend outwardlyof such slots when the cut-ters are in expanded positions, such dogs being provided with noses 19 disposed 'for engagement with the lower end of the casing or the shoe thereon when the dogs project outwardly through the slots.

Referring to Fig. 3, the means E likewise include a' block ornhead 20 provided with a similar bowl or chamber 21, corresponding to the bowl or chamber 10 and similarly coperating with the Shanks 6 of the cutters; such block or Etending stem 22 playing in the chamber extension 5a under the downward urgency of a coil spring 23 constituting the tension member it. The member c comprises dogs pivoted upon pins 2e in slots 25 at the sides of the body A, and having noses 26 rojecting outwardly of such slots when t e cutters are in expanded positions, such dogs lying approximately within the slots when the cutters are in contracted dogs likewise have over-lapping ngers 27 received within an elongated transverse slot- 28 in thelstem 22 and whereby the dogs are inter-engaged with the stem.

yl`he mode of operation and method of use and advantages of the underreamers will be readily understood from the foregoing description taken in connection with the accompanying drawing and the following statement: rlhe forms of construction shown in all the figures operate the same with the exception that the fingers 27 and slot 28, shown in Fig, 3, take the place of the teeth 17 and 1. shownin the other figures. When the reanier is being lowered through the casing the parts are in the positions shown in Fig..

2e' The casing pressing against the cony tracted dogs or .members d holds them within the slots 16, and such dogs in turn hold the steml 13 and'block 9 up against the action of the spring 14, allowing the shank 6 of the cutters to 'rock apart at the lower orifice of the chamber 10 in the head, thus permitting the working ends of the' cutters to fall together or contract, by gravity,rocki upon the shaft-t. When the dogs (l have c eared the casing and the shoe thereon, the pressure of the casing and the shoe is removed from the dogs, and they are free to swing outwardly as the spring 14 pushes the block 9 downwardly, over the shanks' of the cutters, bringing theA shanks together within the bowl or chamber 10' and rocking the cutters', to tilt their working ends outwardly into the expanded positions shown in Fig. 1. The reainer is now in position for service', the up-thrust is taken by the head having a'similar upwardly einI positions. Suchv l shoulders 8 on the body, any out-thrust is taken by the co-engagement'of the Shanks .of the cutters above the shaft 4 and by the engagement of the Shanks of the cutters at their outer surfaces with the wall of the chamber 5, such shank surfaces being faced olf as at 6a to that end; and any iii-thrust is taken by the inner surface of the'bowl 10 ofthe block 9 which has a working fit within the chamber 5; and any down drag is taken by arbor or shaft 4 which'lits within facial socketsA 6* in the inner faces of the Shanks 6 below the shoulders 12. Thecutters are thus solidly braced against all the inuences and stresses encountered in the reaming operation. When the reamer isldrawn upwardly, after use, the dogs d strike the shoe at the lower end of the casing and swing within the slots 1G so as to elevate the stem 13 and block'9 against the pressure of the spring 14. The 4Shanks 6 of the cutters are thus freed to rock apart, the working ends of the cutters swinging in toward each other into collapsed positions as-shown in Fig. 2, so

that the reamer'complete may be withdrawn through the casing. The upper end of with the usual threaded connection 29 whereby it may ybe connected'with vthe string-*o operating tools.

It will be seen expanded' position practically form solid continuations of the body, and coperate with the same through the means D to take up all the thrusts and impacts produced in operating the reamer. There is but little liability of breakage of parts or their displacement and loss in the hole. The method of collapsion and expansion is positive and enables the reamer to be passed through the casing and to enter the casing through the shoe without` di'iculty or obstruction,

the'body A is provided that the cutters when jini:

and

no independent lockino` means or tying de- 4vice is necesary to ho lapsed position, as their outer faces ride over the-inner surface of the casing and shoe without anyinterference with the passage of the reamer through the casing. The particular conformation and shape of the cutters, other than as generally described, does not enter into the invention. lt is mapifest that as to these matters and other features of construction and` combination of parts and features many variations may be made Without departing from the spirit of the in,- vention.

Having thus described my invention l claim and desire to secure by Letters Patent:

l, An underreamer comprising a body provided with a chamber in its lower` end, cutters mounted to rock at the lower end of the body and provided with slianks entendd the cutters in coling upwardly within the chamber above the `named member against the action of the spring; said members being operatively con l vnecteci for joint movement.1 l

'2. An underreamer, comprising a body provided at its lower, end with a chamber, cutters mounted to rock atthe lower end of tbe body and provided with Shanks enter ing the chamber and with cutting portions extending below the body, the cutters and lower end of thebody having coperatingy shoulders to take the rip-thrust of the cutters, a member mounted to play Within the chamber, means urging said member toward the Shanks ot the cutters, said member have ing n pocket receiving and holding the Shanks of the cutters in contracted positions, ande, 'urtlier member projecting outwardly of the body Adnd coperating with the casing to bold the tirst named member against said means urging the same toward'the cutters;

said members being operatively connected for joint movement.

3. An underreamer, compijising :i body provided at its lower cn'd with o. cbnmber und witli'u transverse shult spanning' the lower ortioli of the chamber, cutters mounted) upon said sbult to rock thereon, ld Cutters lmvin0 Shanks proiecting upwardly within the chamber, a b ook mounted to play within the chamber und having ai pocket fitting over the Shanks ot the cutters to hold the working ends of the cutters in expanded positions, a spring acting to uuid the block to the shzuiks of the cutters, :uid means cooperating with tbc block und pro-v jecting outwardly of the body Yfor ongegenient with the casing to hold they block against the pressure of the spring so that the cutters can contract :it their work-iugchris.

In testimony whereof, lY here signed my name to this specification in the presence ol' two subscribing witnesses.

HARRY GEARING.

"Witnesses:

V. J. Coma* I ALFRED'H. Dnunnm. 

